The overall project is divided among 6 primary projects with statistical consultation provided by a 7th faculty member. The project proposes to determine mechanisms whereby pesticides are activated, deactivated, attack the active site, or interact with macromolecules. In addition, environmental actions of pesticides are investigated. Projects concerned with mode of action include investigations on cholinesterases and on oxidative phosphorylation. The main thrust of the cholinesterase work has been toward purification of horse serum cholinesterase. The work on oxidative phosphorylation has been expanded and now includes mammalian mitochondria as well as plant mitochondria and chloroplasts. Projects on metabolism include purification of glutathion transferases and separation of optical isomers of certain OP insecticides. Other work on metabolism includes characterization and purification of cytochrome P-450. A final project concerning molecular toxicology involves determination of association constants of serum proteins and certain pesticides. In the environmental studies under investigation, a system to monitor genetic aspects of pesticides with two model systems has been devised. Additionally, projects concerned with hazards of reentry of agricultural workers into pesticide-treated fields are undertaken. BIBLIOGRAPHIC REFERENCES: Guthrie, F. E., J. J. Domanski, A. R. Main, D. G. Sanders, and R. J. Monroe. 1974. Use of mice for initial approximation of reentry intervals into pesticide-treated fields. Arch. Environ. Contam. Toxicol. 2:233-242. Skalsky, H. L., and F. E. Guthrie. 1975. Bindings of insecticides to macromolecules in the blood of the rat and American roach. J. Pest. Biochem. Physiol. 15:27-34.